Methods, compositions and systems for enhancing the useful life of a transportation surface

ABSTRACT

Methods, compositions and systems for prolonging the lives of transportation surfaces, including pavement, runways, bridges and parking structures include chemically protecting the transportation surfaces. Chemical protection may be accompanied by physical alteration of the transportation surface, which may enhance one or both of a microtexture and a macrotexture of the transportation surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 13/559,564, filed on Jul. 26, 2012, and titled METHODS, COMPOSITIONS AND SYSTEMS FOR ENHANCING THE USEFUL LIFE OF A TRANSPORTATION SURFACE (“the '564 application”). The '564 application includes a claim for the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 61/511,603, filed on Jul. 26, 2012, (“the '603 Provisional Application”), and to U.S. Provisional Patent Application No. 61/643,219, filed on May 4, 2012 (“the '219 Provisional Application”). The entire disclosures of the '564 application, the '603 Provisional Application and the '219 Provisional Application are hereby incorporated herein.

TECHNICAL FIELD

This disclosure relates generally methods, compositions and systems for prolonging the lives of transportation surfaces, including pavement, runways, bridges and parking structures. More specifically, this disclosure relates to the use of techniques for physically altering the top of a transportation surface in conjunction with the use of chemical protectants on the transportation surfaces to improve the useful lives of the transportation surfaces.

RELATED ART

Conventionally, when a new transportation surface, such as pavement, a runway, a bridge or a parking structure, is laid, the transportation surface has a macrotexture, which is visible to the naked eye. The macrotexture of a transportation surface may be formed in a top of the transportation surface while the transportation surface is formed. A variety of processes may be used to form macrotecture, including tinning, raking, chain dragging, burlap drag, brooming and the like. Macrotexture may impart the top of the transportation surface with skid resistance and provide recesses into which liquids (e.g., water, etc.) may flow. In addition, the macrotexture may provide channels that enable liquids to flow off of and away from the transportation surface. In any event, the macrotexture of a transportation surface may prevent the collection, or pooling, of liquids on surfaces where friction (e.g., with the tires of vehicles traveling across the transportation surface, etc.) is desired and, thus, may reduce hydroplaning and, thus, enable the transportation surface to maintain its frictional characteristics in wet weather conditions.

In addition to macrotexture, new transportation surfaces also include microtexture. Microtexture typically includes the fine roughness features on the aggregate of a transportation surface, as well as smaller particles, such as fine sands. These features are often barely, if at all, visible to the naked eye. The fine roughness features of microtexture provide the majority of the friction (i.e., skid resistance) that is usually desired on transportation surfaces.

Over time, weather, use, and a variety of other factors diminish the quality of transportation surfaces, including their microtexturing and, often, their macrotexturing. This is particularly true on diamond ground surfaces, which often lose macrotexturing with age when they are located in climates where wet and freezing conditions are common. As vehicles travel over transportation surfaces, their tires generate friction that causes those surfaces to wear. In addition to wearing the transportation surface, small pieces of rubber that are worn from the tires and other debris become trapped in fine roughness features of the microtexture, effectively smoothing or polishing removing the texture of the pavement. Transportation surfaces that are exposed to harsh conditions (e.g., extremes in weather, prolonged periods of snow and/or ice, etc.) wear particularly quickly.

The damaging effects of wear, water and freeze/thaw cycles cause transportation surfaces to lose their texture (e.g., macrotexture) over time, which may distress the transportation surface. Initial scaling (i.e., the flaking or peeling of the finished surface) and/or cracking may lead to aggregate pop-outs, which may then lead to spalling. Once the top of the transportation surface begins to erode, other issues arise, such as early rutting, corrosion of rebar within the transportation surface and alkali silica reactivity (ASR).

In recent years, a variety of retexturing techniques have been used in an effort to restore the microtexture and, sometimes, the macrotexture of a worn transportation surface, as well as to eliminate unevenness, rutting and/or surface deterioration. Retexturing often requires the removal of a layer of material from the top of the transportation surface, a process known in the art as “re-profiling” (e.g., by grinding (e.g., with a diamond grinder, etc.), a combination of grinding and grooving (e.g., with a diamond groover, etc.), etc.), which may expose more porous underlying portions of the transportation surface. Consequently, a retextured transportation surface may be more prone to wear or other damage than a new transportation surface, necessitating the need for further retexturing in a shorter period of time. It is generally accepted that a transportation surface may be re-profiled up to three times. However, re-profiling may cause fatigue, which may lead to further damage to the transportation surface.

Weather (e.g., freezing and thawing, etc.) and other conditions (e.g., use of de-icing chemicals, the use of tire chains, etc.) may also cause transportation surfaces to crack and/or scale. Conventionally, cracks and scaling have ultimately lead to more extensive damage to the pavement and have required costly repairs, which often include the removal of material from the top of a transportation surface and the formation of an overlay, or cutting out sections of the transportation surface, along with doweling and replacement.

When retexturing will not restore the desirable characteristics of a transportation surface, more drastic measures must be taken. Conventionally, such measures include removal (e.g., by diamond grinding and, optionally, grooving; etc.) and replacement (e.g., forming an overlayment of a transportation surface material on the remaining portion of the existing transportation surface; doweling and patching; wearing course; etc.) of the damaged surface in a partial depth repair process known as “overlaying.” Alternatively, one or more sections of the transportation surface may be completely removed and replaced.

SUMMARY

The present disclosure relates to methods, compositions and systems for enhancing the life of a transportation surface (e.g., a vehicular pavement, such as a highway or a road; a highway ramp, a bridge deck; a runway; a pedestrian walkway; etc.). The disclosed methods, compositions and systems may be used on transportation surfaces formed from a variety of different materials, including, without limitation, concrete and asphalt.

The life of a transportation surface may, in various embodiments, be enhanced by imparting the transportation surface with wear and abrasion resistance, or increased durability. These characteristics may reduce the rates at which age, climate conditions (e.g., wet weather, freeze/thaw conditions, etc.), maintenance (e.g., snow removal, deicing, etc.), abrasion and use cause the transportation surface to incur rutting, scaling, cracking, or spalling or to lose skid resistance or otherwise deteriorate.

A method for enhancing the life of a transportation surface may include chemically protecting the transportation surface. Such chemical protection may include hardening and/or densifying a surface of the transportation surface. Hardening and/or densification may include the application of a hardener/densifier, such as a lithium-based product (e.g., lithium polysilicate, colloidal silica, etc.) or any other suitable hardener/densifier (e.g., magnesium fluorosilicate (i.e., magnesium silicofluoride); another metal silicate, such as potassium silicate or sodium silicate; etc.), to the transportation surface. Chemical protection may be effected without diminishing the frictional characteristics of the transportation surface. In some embodiments, chemical protection of a transportation surface may be effected alone; i.e., without any other treatment, such as physical alteration of the transportation surface. Optionally, a transportation surface may be treated with a protective compound that prevents scaling of the transportation surface, a compound that protects the transportation surface from corrosive agents, a protective compound that seals the transportation surface (i.e., prevent migration of moisture therein), or a compound that otherwise extends the useful life of the transportation surface.

Different types of protection may be combined in simultaneous or sequential application to the transportation surface. As an example, an anti-corrosive chemical (e.g., lithium nitrate, etc.) and/or a sealer (e.g., silane, etc.), may be applied and permitted to penetrate into the transportation surface before a hardener/densifier, such as a colloidal silica, a lithium polysilicate, another metal silicate or magnesium fluorosilicate, is applied to the transportation surface. In some embodiments, the hardener/densifier may be applied to the transportation surface before the anti-corrosive chemical and/or sealer cures or otherwise dries.

In other embodiments, chemical protection of a transportation surface may accompany physical alteration of the transportation surface. Physical alteration of a transportation surface may include enhancement (e.g., restoration, improvement, etc.) of a texture of the transportation surface, or an increase in a surface area of a top of the transportation surface. Some embodiments of physical alteration include increasing a so-called “microtexture” of the transportation surface. Microtexture includes the microscopic roughness (e.g., roughness features with a texture relief of less than about 0.5 mm) of the transportation surface. A so-called “macrotexture” of the transportation surface, which includes larger features, such as projections, depressions, grooves, and the like, visible to the naked eye (e.g., features having a texture relief of about 0.5 mm or more) are increased in some embodiments. Physical alteration, including enhancement of the microtexture of the transportation surface, may include the removal of material from the top of the transportation surface, and may include increasing porosity at the top of the transportation surface. Material removal may be accomplished mechanically (e.g., by shot blasting; grinding; grooving; abrasion; etching; pressure washing, or spraying; etc.), chemically or otherwise.

When physical alteration and chemical protection processes are used in conjunction with one another to enhance a transportation surface, the physical alteration may precede the chemical protection. Alternatively, the physical alteration and chemical protection may be concurrently effected. In such embodiments, the chemical protection may inhibit further damage to the physically altered (e.g., texture-enhanced, restored, etc.) surface. A physically altered transportation surface may be chemically protected by hardening and/or densifying a top of the transportation surface, preventing scaling at the top of the transportation surface, protecting the transportation surface from corrosive agents, sealing the transportation surface, or otherwise treating the transportation surface in a manner that extends its life. The transportation surface may be chemically protected without undesirably diminishing the frictional characteristics obtained by its physical alteration.

The disclosed processes may be used to improve a new transportation surface (e.g., new pavement; a new overlay, or topper (e.g., white top, blacktop, etc.); etc.). When used to enhance the useful life of a new transportation surface, a disclosed method (e.g., chemical protection and optional physical alteration) may be effected after an initial cure of transportation surface, within thirty (30) days after placement of the transportation surface, or at any other appropriate time. In some embodiments, light shot blasting may be used to facilitate the release and removal of a curing agent from the top of a transportation surface while increasing a microtexture of the transportation surface. The light shot blasting may be accompanied by or followed by chemical protection.

Methods of this disclosure may also be used to refresh an existing transportation surface. An existing transportation surface may be refreshed following the passage of a predetermined event. Over time, the refreshing process may be repeated at least once, again upon the passage of one or more predetermined events.

In some embodiments, an existing transportation surface may be refreshed following the passage of a predetermined period of time, or periodically, to extend its useful life. Without limitation, an existing transportation surface (e.g., pavement, an overlay, or topper, etc.) may be refreshed about one year to about three years of the original placement of the transportation surface. As another example, an existing transportation surface may be refreshed about one year to about two years after the existing transportation surface has been re-textured or otherwise physically altered, and again every year or two thereafter. An existing transportation surface may also be refreshed about one year to about two years after it was previously refreshed.

In other embodiments, the predetermined event may be when wear of the existing transportation surface becomes apparent (e.g., tines on the surface are worn, ruts begin to form on tire paths, etc.), when the microtexture and/or macrotexture of the existing transportation surface is insufficient or when wear on the surface, or surface polishing, renders the existing transportation surface close to unsafe or unsafe (e.g., the surface has an undesirably low skid number, etc.).

In still other embodiments, the predetermined event may comprise a predetermined threshold for a certain, or pre-specified, condition. More specifically, the certain, or pre-specified condition may be a condition that, over time, is known to cause surface polishing of the existing transportation surface, or that may cause the existing transportation surface to wear or to erode, or otherwise damage the existing transportation surface.

The process of refreshing an existing transportation surface may include the application of a hardener/densifier to the existing transportation surface. The hardener/densifier may be applied to the entire surface, or its application may be limited to specific regions (e.g., tire paths, ruts, etc.). The process of refreshing an existing transportation surface may be preceded or otherwise accompanied by physical alteration of the existing transportation surface (e.g., by pressure washing, or spraying; use of abrasives; shot blasting; grinding; grooving; etc.).

In another aspect, this disclosure relates to protective compounds for chemically protecting a transportation surface. In some embodiments, a protective compound may be configured or formulated to harden and/or densify a transportation surface (e.g., it may include a lithium polysilicate, a sodium silicate, a potassium silicate, etc.). More specifically, such a protective compound may include a lithium-based densifier, such as a lithium polysilicate or a colloidal silica, another metal silicate or any other suitable hardener/densifier. In addition to the hardener/densifier, such a protective compound may include an anti-scaling agent (e.g., a metal siliconate, such as a transition metal siliconate, a post-transition metal siliconate, an alkali metal alkyl siliconate (e.g., potassium methyl siliconate, potassium propyl siliconate, sodium methyl siliconate, etc.), a magnesium fluorosilicate, etc.) and/or a sealer (e.g., silane, etc.), as well as water. In some specific embodiments, the composition may include, consist essentially of, or even consist of a hardener/densifier (e.g., a metal silicate, magnesium fluorosilicate, etc.), a metal siliconate, silane and water.

According to another aspect, a system for enhancing the useful life of a transportation surface may include a physical alteration component for physically altering a top of the transportation surface and a protective compound for chemically protecting the transportation surface. Among a variety of possible embodiments, the physical alteration component may comprise a shot blaster, a diamond grinder, a diamond groover, a diamond grinder/groover, an abrasive blaster (e.g., a sand blaster, etc.), a pressure washer, or the like. Embodiments of compounds for chemically protecting the transportation surface include, but are certainly not limited to, hardeners and/or densifiers, anti-scaling agents and/or sealers.

Other aspects, as well as features and advantages of various aspects, of the disclosed subject matter will become apparent to those of ordinary skill in the art through consideration of the ensuing description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is schematic representation of an embodiment of a system for extending the useful life of a transportation surface;

FIGS. 2A and 2B are, respectively, images of a surface prior to treatment with a lithium-based hardener/densifier embodiment of a protective compound and after treatment with the lithium-based hardener/densifier;

FIG. 3 is a graph depicting the effect of an embodiment of a method for extending the useful life of a transportation surface on the safety of the transportation surface; and

FIGS. 4 and 5 are graphs depicting the protection that a protective compound may provide for a transportation surface.

DETAILED DESCRIPTION

FIG. 1 illustrates an embodiment of a system 10 for enhancing, or improving, a useful life of a transportation surface S, such as pavement, a runway, a bridge, a parking structure, or the like. The system 10 includes a physical alteration component 20, a protective compound 30 and, optionally, an applicator 40 for introducing the protective compound 30 onto the transportation surface S.

The physical alteration component 20 may comprise any apparatus that will alter the texture of a transportation surface S. In some embodiments, the physical alteration component 20 may be configured to increase or at least partially restore microtexturing of the transportation surface S. A physical alteration component 20 may increase microtexturing by generating a physical impact against the transportation surface S. Non-limiting examples of such a physical alteration component 20 include shot blasting equipment (e.g., that available from Blastrac, N.A., of Oklahoma City, Okla., etc.) and grinding equipment (e.g., the diamond grinding equipment available from Diamond Surface, Inc., of Rogers, Minn., etc.). As another option, a physical alteration component 20 may chemically increase microtexturing (e.g., by etching the transportation surface S, etc.). Microtexturing may be restored by a physical alteration component that forces contaminants (e.g., particles of rubber, dirt, oil, etc.) from microtexturing that may already be present in the transportation surface S. A couple of examples of such a physical alteration component 20 include, but are not limited to, abrasive blasting equipment (e.g., sand blasting equipment, etc.) and pressure washing, or spraying, equipment. In some embodiments, the physical alteration component 20 (e.g., a grinder and/or a groover, etc.) may also increase macrotexturing of the transportation surface S or impart the transportation surface with macrotexturing.

Once a transportation surface has been physically altered, it may be cleaned (e.g., by pressure washing, or spray; etc.). Cleaning may remove bitumen residues or buildup on the aggregate, thereby exposing microtexture and, thus, enhancing the performance of the physical alteration process.

The applicator 40 of a system 10 for enhancing a useful life of a transportation surface S may be configured to apply a protective compound 30 in the form of a liquid or a slurry. In some embodiments, the applicator 40 may be configured to spray the protective compound 30 onto a transportation surface S. Such an applicator 40 may be configured to spray the protective compound 30 under sufficient pressure (e.g., 750 psi to 30,000 psi, or 5 MPa to 200 MPa, or more, etc.) to expose microtexturing in the transportation surface S. Alternatively, the applicator 40 may be configured to generate a relatively low pressure spray of protective compound 30. In other embodiments, the application 40 may be configured to drop a stream of protective compound 30 onto a transportation surface S, to roll protective compound 30 onto a transportation surface S, or to apply the protective compound 30 to a transportation surface S in any other acceptable manner.

The protective compound 30 may comprise any type of compound that will protect the transportation surface S and prevent wearing of or damage to the same. In a specific embodiment, the protective compound 30 may comprise a hardener and/or densifier. As other options, a protective component 30 may prevent scaling of the transportation surface S, protect the transportation surface S from corrosive agents, seal the transportation surface S, or otherwise extend the useful life of the transportation surface S. In some embodiment, the protective compound 30 may be configured to perform a combination of these functions.

In embodiments where the protective compound 30 hardens and/or densifies the transportation surface S, it may include a lithium-based hardener/densifier. Examples of lithium-based hardener/densifiers include lithium polysilicates and colloidal silicas. When applied to a concrete surface, lithium-based hardener/densifiers penetrate pores and microcracks in the surface. The lithium of lithium-based hardener/densifiers stabilizes the silicate, enabling it to remain in solution for a sufficient time (i.e., longer than sodium silicates since lithium ions are believed to stabilize more silica in the colloidal state than sodium ions) to penetrate the pores and/or microcracks in the concrete and to react with calcium hydroxide.

In other embodiments, other types of hardener/densifiers may be used as the protective compound 30, including, without limitation, other metal silicates (e.g., sodium silicates, potassium silicates, etc.), magnesium fluorosilicate and other suitable materials. As an example of the use of magnesium fluorosilicate as the protective compound 30, the magnesium fluorosilicate available from BASF Corporation of Florham Park, N.J., as LAPIDOLITH® and as MASTERKURE® HD 300WB or that available from The Euclid Chemical Company of Cleveland, Ohio as SURFHARD® may be used. The magnesium fluorosilicate may be diluted to a suitable concentration (e.g., one part magnesium fluorosilicate to two parts water, one part magnesium fluorosilicate to one part water, two parts magnesium fluorosilicate to one part water, etc.). Application of the magnesium fluorosilicate to a transportation surface may occur as a single coat or a plurality of coats (e.g., three coats, etc.) may be applied. Suitable application rates include up to 100 square feet per gallon (ft²/gal) (i.e., about 2.5 m²/L) for extremely porous concrete.

As a silicate reacts with calcium hydroxide, calcium silicate hydrate (the same product produced when water is added to Portland cement) is formed. As a comparison of FIG. 2A (untreated concrete surface) to FIG. 2B (hardened/densified concrete surface) demonstrates, calcium silicate hydrate chemically hardens, reduces the porosity of, and densifies the surface of the concrete, which increases the surface strength of the concrete, as well as the ability of the concrete to resist wear from abrasion. The greater the porosity at the surface, the further the lithium-based hardener/densifier will penetrate into the concrete. Moreover, hardener/densifiers, including, without limitation, lithium-based hardener/densifiers, may react with the mineral make up of various aggregates (e.g., aggregates used in cementitious materials, such as concrete; aggregates used in asphalts (particularly lime-based aggregates); etc.) while enhancing the hardness of the aggregates. The residue from lithium-based hardener/densifiers is a dust, which is more easily removed from a treated surface than the residues of other alkali metal silicates, which form crusts on concrete surfaces.

A protective compound 30 that has been formulated to prevent scaling may be configured to render the transportation surface more water-resistant, or to facilitate drying of the transportation surface. An anti-scaling protective compound 30 may include a component that reacts with a material of the transportation surface to strengthen the same. By way of non-limiting example, a protective compound 30 may include a metal siliconate (e.g., a transition metal siliconate, a post-transition metal siliconate, an alkali metal alkyl siliconate, etc.).

Anti-corrosive agents that may be useful as at least part of a protective compound 30 include, without limitation, nitrates or nitrites. In a specific embodiment, a protective compound 30 may include lithium nitrate, which may prevent or counteract the effects of alkali silica reactivity (ASR).

A sealer (i.e., an agent that prevents migration of moisture into a transportation surface) may be designed to penetrate and absorb into the pores and microfissures of the minerals from which aggregates (e.g., of cementitious materials, such as concrete; of asphalt; etc.) are formed, which may react in a manner that provides an insoluble structure that fortifies and strengthens the aggregate. Silane is an example of a sealer that may be included in a protective compound 30.

Protective compounds 30, such as hardener/densifiers and/or sealers, that chemically and/or structurally reinforce the aggregate of a transportation surface may increase the durability and safety of the transportation surface.

The following EXAMPLES provide formulations for various embodiments of protective compound 30:

Example 1

Component Amount (percentage, by weight) Lithium polysilicate about 20% Alkali Metal Siliconate (sodium about 6% to about 15% methyl siliconate, potassium methyl siliconate or potassium propyl siliconate) Silane about 2% Water Balance

Example 2

Component Amount (percentage, by weight) Colloidal silica about 15% Alkali Methyl Siliconate about 15% Silane about 2% Water Balance

With returned reference to FIG. 1, various embodiments of protective compounds 30 that are within the scope of this disclosure and, optionally, various embodiments of systems 10 that are within the scope of this disclosure may be used in a variety of techniques for enhancing, or improving, the useful lives of transportation surfaces S.

A protective compound 30 and, optionally, a system 10 may be used to enhance, or improve, the useful life of a new transportation surface S, which may include new pavement, a new overlay, a topper (e.g., white top, blacktop, etc.) or the like. Processes that provide such enhancement may be carried out after an initial cure of transportation surface S, within thirty (30) days after placement of the transportation surface S, or at any other appropriate time. In some embodiments, the protective compound 30 may be applied to a new transportation surface S that has not been processed or modified. In other embodiments, prior to applying the protective compound 30 to the new transportation surface S, the new transportation surface S may be processed or modified. More specifically, the new transportation surface S may be physically altered (e.g., with a physical alteration component 20, etc.). Even more specifically, light shot blasting and/or abrasive blasting may facilitate the release and removal of a curing agent from the top of the new transportation surface S and/or increase a microtexture of the new transportation surface S.

A protective compound 30 and, optionally, a system 10 may also be used to enhance, or improve, the useful life of an existing transportation surface S. Stated another way, the protective compound 30 and, optionally, the system 10 may be used to refresh an existing transportation surface S. An existing transportation surface S may be refreshed simply by applying a protective compound 30 to it; i.e., the process of refreshing the existing transportation surface S may consist of or consist essentially of application of the protective compound 30. Alternatively, an existing transportation surface S may be refreshed by processing or modifying (e.g., physically altering, etc.) the existing transportation surface S before the protective compound 30 is applied to the existing transportation surface S. When an existing transportation surface S is refreshed repeatedly over time, it may be refreshed with only a protective compound 30 on some occasions, and with both surface processing or modification and application of a protective compound 30 on other occasions. Refreshment of an existing transportation surface S may occur when suitable conditions (e.g., lack of freeze-thaw conditions, consistently desirable temperatures, lack of heavy precipitation, etc.) are likely to persist (e.g., during the late spring, during the summer, in early autumn, etc.).

The extent to which an existing transportation surface S is refreshed may be based on the materials from which the transportation surface S is formed (e.g., concrete, asphalt, etc.); the hardness of aggregate, if any; used in the existing transportation surface S; the type of refreshment that performed during a previous refreshment, if any; the conditions to which the existing transportation surface S has been subjected since its previous refreshment; and/or any other useful factors. As an example, an initial refreshment of an existing transportation surface S may consist of application of a protective compound 30 to the existing transportation surface S. A subsequent refreshment may include cleaning the existing transportation surface S (e.g., by pressure washing, or spraying; etc.) before applying a protective compound 30 and/or while applying the protective compound 30 to the existing transportation surface S. The next time the existing transportation surface S is refreshed, it may be physically altered (e.g., by sand blasting, shot blasting, etc.) before and/or during application of a protective coating 30. Even more drastic physical alteration of the existing transportation surface S may occur (e.g., by grinding, grooving, etc.) the next time it is refreshed with a protective compound 30.

In some embodiments, an existing transportation surface S may be refreshed periodically. Periodic refreshment of an existing transportation surface S may occur before surface polishing, wear, erosion and/or other damage is seen or otherwise detected (e.g., about one year to about three years after initial placement of the transportation surface S, etc.). Without limitation, an existing transportation surface S may be refreshed on an annual basis (i.e., about once a year), on a biannual basis (i.e., about once every two years), at any other suitable frequency (e.g., every five years, etc.) or in any other suitable pattern of time (e.g., two years, four years, five years, seven years, eight years and ten years after initial placement of the surface; etc.). In other embodiments, including on existing transportation surfaces S where rutting is likely to occur, a protective coating 30 may be applied to the wheel paths annually or biannually. Application of the protective coating 30 to the tire paths on an existing transportation surface S may occur without applying the protective coating 30 to other areas of the existing transportation surface S.

In other embodiments, an existing transportation surface S may be refreshed based on the climate and other conditions to which the existing transportation surface S has been exposed. In some embodiments, the existing transportation surface S may be refreshed once a predetermined threshold has been met for one or more conditions. As a non-limiting example, an existing transportation surface S that has been subjected to cold weather conditions may be refreshed after one or more predetermined cold weather threshold conditions have been met. As a further example, the existing transportation surface S may be refreshed as soon as is practical after the existing transportation surface S has been exposed to snow and/or ice for a predetermined number of days. As another example, the existing transportation surface S may be refreshed as soon as is practical after the existing transportation surface S has been exposed to a predetermined number of deicing treatments. As yet another example, the existing transportation surface S may be refreshed once a predetermined number of freeze-thaw cycles (e.g., based on temperature, etc.) have occurred. In a further example, the existing transportation surface S may be refreshed as soon as is practical after the existing transportation surface S has been subjected to a predetermined number of days in which tire chains were required. As these or any other suitable predetermined thresholds may not occur during a single year or even during two consecutive years, refreshment of the existing transportation surface S may not occur every year or even every other year.

As another option, an existing transportation surface S may be refreshed once signs of surface polishing, wear, erosion and/or other damage are seen or otherwise detected. The manner in which the existing transportation surface S is refreshed may be based on the conditions that have led to its refreshment. When tines, if any, on the existing transportation surface S show initial signs of wear, the existing transportation surface S may be refreshed simply by application of a protective compound 30 (i.e., refreshment of the existing transportation surface S may consist of applying the protective compound 30 to the existing transportation surface S). In another example, if surface polishing is evident (e.g., when the microtexture and/or macrotexture of the existing transportation surface S is visibly diminished, etc.), the existing transportation surface S may be cleaned (e.g., by pressure washing, or spraying; etc.) or physically altered (e.g., abrasively blasted, shot blasted, etc.) before or while a protective compound 30 is applied to the existing transportation surface S. As another example, an existing transportation surface S that is beginning to show rutting along tire paths (which rutting may start to appear about five to about seven years after placement of the transportation surface S, and may increase exponentially thereafter) may be refreshed by applying a protective compound 30 onto or into the tire paths, but not onto other areas of the existing transportation surface S (which may increase the useful life of a rutted surface by about two years or more). More drastic wear or damage to an existing transportation surface S (e.g., an existing transportation surface S that is close to being unsafe or is unsafe, such as by having an undesirably low skid number or the like, etc.) may be addressed by physically altering the existing transportation surface S to an extent that corresponds to the wear or damage (e.g., by abrasively blasting, shot blasting, grinding or grooving the existing transportation surface S, etc.) and then applying a protective compound 30 to the physically altered transportation surface S.

The foregoing techniques for determining when to refresh existing transportation surfaces S may also be used in combination with each other. As a non-limiting example, the first time an existing transportation surface S is refreshed may follow detection of surface polishing, wear, erosion or other damage or it may follow once a certain condition has met a predetermined threshold, while subsequent refreshments may occur on a periodic basis. As another non-limiting example, an existing transportation surface S may be refreshed periodically or in accordance with a time pattern unless predetermined thresholds are met for one or more conditions before the next refreshment is scheduled to occur, in which case the existing transportation surface S may be refreshed before it is scheduled to be refreshed, and the schedules for subsequent refreshments may also be adjusted. Other combinations of techniques for determining when to refresh transportation surfaces S are also within the scope of this disclosure.

Various studies have been performed to determine the effectiveness of the disclosed techniques in enhancing or extending the useful lives of transportation surfaces. The EXAMPLES that follow provide further insight in various embodiments and aspects of the disclosed subject matter.

Example 3

The California Department of Transportation (Caltrans) sponsored experimental research in which concrete pavement wear on a test section of U.S. Interstate Highway 80 (“I-80”) over Donner Pass was evaluated over a twelve (12) month period of time. It is well known that the Donner Pass section of I-80 experiences some of the harshest conditions in the United States in terms of snow-removal, tire chains and tire studs, and deicing salts. As expected, during the test and observation period, the test section was subjected to frequent snow plowing, traffic with snow chains and traffic with studded tires.

The test section included a three lane wide, one mile long section of I-80 at Donner Pass. It was divided into three subsections. Prior to treatment and testing, rut depths were measured at locations in each of the three subsections. A first of the three subsections served as a control; it was not subjected to physical alteration or chemically protected. A second of the three subsections was not physically altered, but was treated with a lithium polysilicate hardener/densifier. The third subsection was shot blasted, then treated with the lithium polysilicate hardener/densifier. Twelve (12) months after treatment, rut depths were again obtained from different locations across the three subsections. The results are set forth in the following table:

TABLE 1 Wear Core ID Treatment Wear (in.) Wear (in.) (mm) C1 No shot blasting; no 0.1875 3/16 0.7382 hardener/densifier (Control) C3 Control 0.2500 ¼ 0.9843 C4 Control 0.2500 ¼ 0.9843 C6 Control 0.2500 ¼ 0.9843 C10 Control 0.1250 ⅛ 0.4921 C12 Control 0.1875 3/16 0.7382 Average Wear of Control Section 0.2083 3/16+ 0.8202 D1 Densifier over shot blasting 0.0625 1/16 0.2461 (DOS) D3 DOS 0.1250 ⅛ 0.4921 D5 DOS 0.0625 1/16 0.2461 D6 DOS 0.0625 1/16 0.2461 D7 DOS 0.0000 0 0.0000 D8 DOS 0.0625 1/16 0.2461 Average Wear of DOS Section 0.0625 1/16 0.2461

As TABLE 1 illustrates, the physically altered and chemically protected subsection exhibited only about one third the wear of the untreated control subsection. These results indicate that the lithium polysilicate hardener/densifier has delayed loss of and damage to the material of the transportation surface, suggesting that the polysilicate hardener/densifier has reduced the porosity of the transportation surface and improved its hardness. Further, because the rate of wear has been significantly reduced by the lithium polysilicate hardener/densifier, these results suggest that physical alteration of the transportation surface has improved pavement friction and aggregate skid resistance.

Example 4

In other experimentation, a thirty-three (33) month field test sponsored by the Oklahoma Department of Transportation was conducted along a section of U.S. Highway 77 (“US-77”) near Oklahoma City, Okla. to confirm that a protective compound, a lithium-based hardener/densifier, does not present a safety threat when applied to transportation surfaces. The section of US-77 that was tested included concrete pavement, and was divided into two subsections: a first of which had been subjected only to shot blasting and a second of which had been subjected to shot blasting and chemical protection with a lithium-based hardener/densifier.

During the course of the study, skid numbers were obtained from each subsection on a monthly basis (thirty-three (33) months for the shot blast-only treated surface; twenty-six (26) months for the shot blast and a lithium-based hardener/densifier-treated surface). The results, which are depicted by FIG. 3, demonstrate that the application of a lithium-based hardener/densifier to a physically altered transportation surface only marginally decreases the skid number of the transportation surface. Nonetheless, the skid number (approximately 44) of that subsection remained well above safe limits and, thus, the lithium-based hardener/densifier did not compromise the safety of the transportation surface. These results indicate that the application of a protective compound to a physically altered transportation surface will not substantially diminish the skid number, or frictional characteristics, of the transportation surface.

Example 5

In another study, the abilities of embodiments of the materials set forth in EXAMPLES 1 and 2 to prevent scaling of concrete surfaces were evaluated. In that study, forty-eight (48) plastic tubs, each having an inside dimension of 7.5 inches by 12.5 inches, were filled with a concrete mixture (at a w/cm ratio of 0.45 and including 564.00 lb/yd³ cement type I/II, 1207.00 lb/yd³ sand, 1807.00 lb/yd³ aggregate #1, 254.00 lb/yd³ water and a design air content of 6.5%) to a depth of 3 inches. The concrete within each tub was then finished with a broom. The concrete within each tub was flooded with water, then the tub and the concrete therein were covered and stored at room temperature (23° C.±2° C.) for fourteen (14) days, during which the concrete moist-cured.

After the fourteen (14) day moist cure, the concrete samples were removed from their tubs and air dried at room temperature (23° C.±2° C.) and fifty percent (50%) relative humidity for seven (7) days (i.e., until the samples were twenty-one (21) days old. The inside surfaces of the plastic tubs were abraded.

At the end of that seven (7) day period, each concrete sample was secured within a plastic tub with NOVALINK concrete caulk, which was applied around the top side and edge of each concrete sample. The caulk was permitted to cure for three (3) days. At this point, the concrete samples were twenty-four (24) days old.

At that point in time, a protective compound according to EXAMPLE 1 was applied to top surfaces of a first test group of sixteen (16) of the concrete samples, while a protective compound according to EXAMPLE 2 was applied to the top surfaces of a second test group of sixteen (16) of the concrete samples. The protective compounds of EXAMPLES 1 and 2 were applied at a volume equivalent to one gallon/150 ft³ of concrete. The concrete samples were then allowed to sit for four (4) days. An equivalent amount of water was applied to the remaining sixteen (16) concrete samples, which served as a control group.

Two of the concrete samples of each group were reserved as controls, to which 400 ml of water was applied. Volumes of 400 ml of seven (7) different deicing chemicals were applied to two more concrete samples from each group. The deicing chemicals that were used included: (1) the calcium chloride deicer available as DOWFLAKE from The Dow Chemical Company of Midland, Mich.; (2) the magnesium chloride hexahydrate deicer available as DUSTGARD® from Compass Minerals America Inc. of Overland Park, Kans.; (3) the potassium acetate deicer available as CRYOTECH E-36® from Cryotech Deicing Technology of Fort Madison, Iowa; (4) the lithium potassium acetate deicer available as LITHMELT® from the Lithium Division of FMC Corporation of Philadelphia, Pa.; (5) the beet juice extract deicer available as Gen-3-64/Di-H2O (D3) from Basic Solutions North America Corp. of Toronto, Ontario, Canada; (6) kosher salt (NaCl) available from Cargill, Incorporated, of Minnetonka, Minn., under the brand DIAMOND CRYSTAL®; and (7) the calcium magnesium acetate deicer available as CMA® Deicer from Cryotech.

With the water and deicers on the concrete samples, they cycled between a temperature of −18° C. for about sixteen (16) hours and a temperature of 23° C.±8° C. for eight hours. After the completion of five of these freeze/thaw cycles, the concrete samples were flushed with tap water, and the eroded aggregate and paste were collected in funnels; one funnel corresponding to each concrete sample. Each time aggregate and paste were collected, they were dried overnight at a temperature of about 38° C. and their weight was determined and recorded. This process was completed five (5) times for each concrete sample, subjecting each concrete sample to a total of twenty-five (25) freeze/thaw cycles and five (5) measurements. The collective amounts of paste and aggregate from each sample were weighed to provide an indication of the effectiveness of the protective compounds of EXAMPLE 1 and EXAMPLE 2 against no chemical protection and against one another when exposed to various deicers. FIGS. 4 and 5 illustrate the cumulative weight loss from the various concrete samples, and demonstrates that the compounds of EXAMPLE 1 and EXAMPLE 2 actually prevented erosion of the concrete samples, with the composition of EXAMPLE 1 performing slightly better than the composition of EXAMPLE 2.

In the past, it has taken about five (5) years to about seven (7) years for new pavement along the Donner Pass section of I-80 to fail (i.e., to develop ruts having a depth of 10 millimeters). When failure occurs, the uppermost surface of the pavement is typically removed and the pavement is white-topped with a thin (e.g., four inch thick, etc.) layer of concrete. However, the predicted service life for a thin layer of white-topped concrete is 6.3 years to 7.1 years. In comparison, as demonstrated by the data provided in EXAMPLE 3, physically altering the same pavement (with shot blasting) and chemically protecting it (with a lithium-based hardener/densifier) significantly increases (e.g., doubles, triples, etc.) the life of the pavement. For new pavement, this could mean a prolonged life of about 9 years to about 21 years, or even longer. Alternatively, treatment of white top in accordance with teachings of this disclosure would also add a significant amount of time to the useful life of the white top. In any event, teachings of this disclosure reduce long-term costs associated with the repair and/or replacement of transportation surfaces, as well as costs associated with disruptions in the flow of traffic.

Although the foregoing description contains many specifics, these should not be construed as limiting the scopes of the inventions recited by any of the appended claims, but merely as providing information pertinent to some specific embodiments that may fall within the scopes of the appended claims. Features from different embodiments may be employed in combination. In addition, other embodiments may also lie within the scopes of the appended claims. All additions to, deletions from and modifications of the disclosed subject matter that fall within the scopes of the claims are to be embraced by the claims. 

What is claimed:
 1. A method for refreshing a transportation surface, comprising: upon passage of a predetermined event, refreshing an existing transportation surface, including applying a protective composition to at least a portion of the existing transportation surface.
 2. The method of claim 1, wherein refreshing the existing transportation surface further includes physically altering the existing transportation surface to increase a microtexture and/or a macrotexture of the existing transportation surface.
 3. The method of claim 1, wherein refreshing the existing transportation surface further includes physically altering the existing transportation surface to increase a skid resistance of the existing transportation surface.
 4. The method of claim 1, wherein the predetermined event comprises a predetermined amount of time after placement of the existing transportation surface and/or after prior refreshment of the existing transportation surface.
 5. The method of claim 1, wherein the predetermined event comprises a predetermined threshold condition.
 6. The method of claim 5, wherein the predetermined threshold condition comprises a predetermined number of freeze-thaw cycles, a predetermined number of days snow and/or ice is present on the existing transportation surface, a predetermined number of applications of a deicer to the existing transportation surface and/or a predetermined number of days tire chain are required to travel over the existing transportation surface.
 7. The method of claim 1, wherein the predetermined event comprises detection of surface polishing, wear, erosion and/or other damage to the existing transportation surface.
 8. The method of claim 7, wherein the predetermined event comprises detection of wear of tines of the existing transportation surface.
 9. The method of claim 7, wherein the predetermined event comprises detection of rutting of the existing transportation surface.
 10. The method of claim 9, wherein applying the protective composition comprises applying the protective composition to ruts and/or tire paths across the existing transportation surface.
 11. The method of claim 10, wherein applying the protective composition to ruts and/or tire paths across the existing transportation surface is effected without applying the protective composition to other areas of the existing transportation surface.
 12. The method of claim 1, wherein applying the protective composition comprises applying the protective composition to ruts and/or tire paths of the existing transportation surface without applying the protective composition to other areas or the existing transportation surface.
 13. The method of claim 1, wherein applying the protective composition comprises applying a protective composition comprising a colloidal silica, a lithium polysilicate, a potassium silicate, a sodium silicate and/or a magnesium fluorosilicate to the existing transportation surface.
 14. A method for refreshing a transportation surface, comprising: upon passage of a predetermined event comprising at least one of: a predetermined amount of time after placement of an existing transportation surface and/or after prior refreshment of the existing transportation surface; a predetermined threshold condition; and/or detection of surface polishing, wear, erosion and/or other damage to the existing transportation surface, refreshing the existing transportation surface, including applying a protective composition to at least a portion of the existing transportation surface, the protective composition comprising at least one hardener/densifier.
 15. The method of claim 14, wherein the predetermined threshold condition comprises a predetermined number of freeze-thaw cycles, a predetermined number of days snow and/or ice is present on the existing transportation surface, a predetermined number of applications of a deicer to the existing transportation surface and/or a predetermined number of days tire chain are required to travel over the existing transportation surface.
 16. The method of claim 14, wherein applying the protective composition to at least the portion of the existing transportation surface comprises applying a protective composition comprising a colloidal silica, a lithium polysilicate, a potassium silicate, a sodium silicate and/or a magnesium fluorosilicate to the existing transportation surface.
 17. The method of claim 14, further comprising: enhancing a microtexture and/or a macrotexture of the existing transportation surface.
 18. The method of claim 17, wherein enhancing the microtexture and/or the macrotexture of the existing transportation surface comprises pressure washing the existing transportation surface, abrasively blasting the existing transportation surface, shot blasting the existing transportation surface, grinding the existing transportation surface and/or grooving the existing transportation surface.
 19. A method for refreshing a transportation surface, comprising: upon passage of a predetermined event comprising at least one of: a predetermined amount of time after placement of an existing transportation surface and/or after prior refreshment of the existing transportation surface; a predetermined threshold condition; and/or detection of surface polishing, wear, erosion and/or other damage to the existing transportation surface, enhancing a microtexture and/or a macrotexture of the existing transportation surface; and refreshing the existing transportation surface, including applying a protective composition to at least a portion of the existing transportation surface, the protective composition comprising at least one hardener/densifier.
 20. The method of claim 19, wherein enhancing the microtexture and/or the macrotexture of the existing transportation surface comprises pressure washing the existing transportation surface, abrasively blasting the existing transportation surface, shot blasting the existing transportation surface, grinding the existing transportation surface and/or grooving the existing transportation surface. 